I noticed that Jordan Adams has not played in the last 2 games (Duke and UC Davis, both losses). I have no idea if she is injured or some other reason.
As mentioned on today's USC broadcast, Jordan Adams is having knee problems and there's a possibility she'll be redshirted. If you've seen her this season, she shot and passed as advertised but really had trouble moving laterally on defense. Considering how this season is going for USC, a redshirt could be a great decision and if Cooper leaves, the next coach will receive the bonus of having Adams for 4 years.
They let women practice against men. Obviously, you don't have to be on the team. I remember, once hearing the women's team practiced against the Warriors Chris Mullin.
I once heard that college-age practice players (female or male) still need to be "qualified" to participate in scrimmages and practices. I don't know if that means that they have to meet the exact same NCAA requirements as the players or some less strict set of requirements. This could have been the area where the violation occurred.
In this case it was a "secondary violation" so that would presumably rule out any egregious violations with high school recruits and so on. I never heard the Chris Mullin story, but we do occasionally hear about alumni who return to give a pep talk and step out onto the court for some instruction. Since they aren't college-eligible, presumably that's OK to some degree.
EDIT: I forgot to mention that I also found it odd that USC chose to trumpet this suspension in a separate story on their website instead of just burying it inside last night's game report. That type of added publicity made me wonder if Cooper's being set up for an exit at the end of this season.